1. Field of the Invention
This invention relates to a screw locking tool, particularly to one including a main body and a screwing element fixed in the accommodating cavity of the main body. When the head of a screw is combined with the receiving groove of the screwing element, the positioning steel balls of the screwing element will be respectively engaged in the side recessed slots of the screw head, and the O-shaped ring of the screwing element will properly push against the positioning steel balls, thus enabling the screwing element to stably fix the screw in place. By so designing, it is needless to provide any magnetic element for attracting and fixing a screw, and before being locked into a work piece, the screw will not slip off, able to carry out screw locking work conveniently, quickly and safely.
2. Description of the Prior Art
One conventional screw locking tool, as disclosed in one U.S. Pat. No. 6,240,811 B1 or in another U.S. Pat. No. 6,539,826 B2, includes a screwing element provided with a clamping jaws 3, 4 disposed in the interior of a holder 2 and respectively formed with an incision 15.16 for clamping the head of a fastener 16. However, the conventional screw locking tool must be provided with clamping jaws for clamping and holding the head of a fastener, complicated in structure and high in manufacturing cost. Such a conventional screw locking tool has the following defects.
1. The clamping jaws of the screwing element are likely to be actuated to contract into the interior of the holder by a little force even if the clamping jaws does not yet clamp a fastener, and in this case, the clamping jaws of the screwing element have to be hooked out by another tool or by the head of a fastener, troublesome in use.
2. The clamping jaws are easy to accumulate iron filings and cause trouble.
Another conventional screw locking tool disclosed in a U.S. Pat. No. 6,324,946 B1, titled “Screwdriver adapter”, includes an adapter 1 provided with a receiving element 3 that is a nut-shaped element 2. The nut-shaped element 2 is disposed with a holding element 15 at a corresponding location of a tool driving means 6 and a resilient element 6. However, such a conventional screw locking tool has to be provided with the tool driving means 6 as a drive portion 18 for driving a screw, and after the screw is locked into a work piece, the drive portion 18 will become excessively lofty and exposed out of the outer surface of the work piece, leaving too many projections on the surface of the work piece.